Things You'll Need
Plastic moisture barrier film
Drywall or paneling
3/4-inch plywood sheathing (optional)
The best approach to insulating an outdoor shed is nearly identical to insulating exterior walls in your home. Advantages to insulating an out building like a shed include better wintering conditions for plant materials and outdoor equipment prone to damage from freezing and thawing. If you must work in an outdoor shed during the winter, the extra insulation will make the space more comfortable.
Remove drywall or paneling sheets covering the wall studs inside the shed.
Measure the height of one channel between two wall studs, from the floor to the crown of the roof, using a measuring tape. Cut a piece of insulation material the same length, using a carpet knife, and tuck it into the cavity between the two wall studs. When extending the insulation up to the crown of the roof, you may want to anchor it with a few strips of duct tape between the two joints.
Fill all the cavities between all the studs around the inside of the shed with insulating material. Avoid "breaking" the insulation and "piecing" it together at junctions or corners. Every break in the blanket or foam sheet presents an opportunity for cold air to leak into the shed.
Cover all the walls with a plastic moisture barrier. Tack the tarp to the wall studs with a staple gun. Seal any seams or tears in the moisture barrier with an adhesive tape made for this purpose.
Install drywall or paneling over the wall studs to "close" the system. Place drywall or paneling all the way to the roof crown.
Burn a candle inside the shed, with the door closed. Pass the candle by the walls and look for tell-tale intrusions of air from the outside. Put out the candle and shoot spray-on insulation into any visible crevices.
Insulation materials vary according to effectiveness, ease in handling, and cost. Solid extruded urethane foam panels are inexpensive and easy to handle, but their “R” insulation factor isn’t especially high. If you use Styrofoam panels, choose the 2-inch thickness for best results. “Fluffy” insulation blankets offer a higher “R” factor but can be more expensive and cumbersome.
Consider raising and insulating the shed floor as well if it is a concrete slab. Build up the floor with 2-by-2-inch dimensional lumber placed over a plastic moisture barrier, insulate between the joists, install a moisture barrier across the top of the studs, and then sheath with ¾-inch plywood.
Some insulation materials made from chemical products can produce side effects. Fiberglass insulation, for example, can cause rashes when the fibers contact the skin.
A writer and entrepreneur for over 40 years, J.E. Myers has a broad and eclectic range of expertise in personal computer maintenance and design, home improvement and design, and visual and performing arts. Myers is a self-taught computer expert and owned a computer sales and service company for five years. She currently serves as Director of Elections for McLean County, Illinois government.